The present invention is generally directed to toners and toner processes, and more specifically, to aggregation and coalescence processes for the preparation of toner compositions, and wherein the charge on the toner can be increased by washing with base followed by an ion exchange in the presence of optional metal oxide particulates, or particles. In embodiments, the present invention is directed to the economical in situ chemical preparation of toners without the utilization of the known pulverization and/or classification methods, and wherein in embodiments toner compositions with an average volume diameter of from about 1 to about 25, and preferably from 1 to about 10 microns, and narrow GSD of, for example, from about 1.15 to about 1.31 as measured on the Coulter Counter can be obtained. The resulting toners can be selected for known electrophotographic imaging, printing processes, including color processes, and lithography. In embodiments, the present invention is directed to a process comprised of dispersing a pigment in an aqueous mixture containing an ionic surfactant in an amount of from about 0.5 percent (weight percent, or parts throughout unless otherwise indicated) to about 10 percent, and shearing this mixture with a latex or emulsion mixture comprised of suspended submicron resin particles of from, for example, about 0.01 micron to about 2 microns in volume average diameter, wherein the resin particles contains an acid functionality in an aqueous solution containing a counterionic surfactant in amounts of from about 1 percent to about 10 percent with opposite charge to the ionic surfactant of the pigment dispersion, and nonionic surfactant in amounts of from about 0 percent to about 5 percent, thereby causing a flocculation of resin particles and pigment particles, followed by heating at about 5.degree. to about 40.degree. C. below the resin Tg and preferably about 5.degree. to about 25.degree. C. below the resin Tg while stirring of the flocculent mixture which is believed to form statically bound aggregates of from, for example, about 1 micron to about 10 microns in volume average diameter comprised of resin and pigment, and thereafter coalescing by heating the formed bound aggregates about above the Tg (glass transition temperature) of the resin. The size of the aforementioned statistically bonded aggregated particles can be controlled by adjusting the temperature in the below the resin Tg heating stage. An increase in the temperature causes an increase in the size of the aggregated particle. This process of aggregating submicron latex and pigment particles is kinetically controlled, that is the temperature increases the process of aggregation. The higher the temperature during stirring the quicker the aggregates are formed, for example from about 2 to about 10 times faster in embodiments, and the latex submicron particles are picked up more quickly. The temperature also controls in embodiments the particle size distribution of the aggregates, for example the higher the temperature the narrower the particle size distribution, and this narrower distribution can be achieved in, for example, from about 0.5 to about 24 hours and preferably in about 1 to about 3 hours time. Heating the mixture about above or in embodiments equal to the resin Tg generates toner particles with, for example, a volume average particle diameter of from about 1 to about 25 and preferably 10 microns. It is believed that during the heating stage (v), the components of aggregated particles fuse together to form composite toner particles. Subsequently, the toner particles are washed in the presence of the base, such that the toner particles, especially the acid functionality present on the toner surface, is reacted with a base to form an acrylic acid salt, which salt can then be ion exchanged in the presence of optional metal oxide particles, to control the toner triboelectrical charge. In embodiments thereof, the present invention is directed to an in situ process comprised of first dispersing a pigment, such as HELIOGEN BLUE.TM. or HOSTAPERM PINK.TM., in an aqueous mixture containing a cationic surfactant, such as benzalkonium chloride (SANIZOL B-50.TM.), utilizing a high shearing device, such as a Brinkmann Polytron, microfluidizer or sonicator, thereafter shearing this mixture with a latex of suspended resin particles containing acid functionality, such as poly(styrene butadiene acrylic acid), poly(styrene butylacrylate acrylic acid), and which particles are, for example, of a size ranging from about 0.01 to about 0.5 micron in volume average diameter as measured by the Brookhaven nanosizer in an aqueous surfactant mixture containing an anionic surfactant, such as sodium dodecylbenzene sulfonate (for example NEOGEN R.TM. or NEOGEN SC.TM., and a nonionic surfactant, such as alkyl phenoxy poly(ethylenoxy)ethanol (for example IGEPAL 897.TM. or ANTAROX 897.TM.), thereby resulting in a flocculation, or heterocoagulation of the resin particles with the pigment particles; and which, on further stirring for about 1 to about 3 hours while heating, for example, from about 35.degree. to about 45.degree. C., results in the formation of statically bound toner aggregates ranging in size of from about 0.5 micron to about 10 microns in average diameter size as measured by the Coulter Counter (Microsizer II), where the size of those aggregated particles and their distribution can be controlled by the temperature of heating, for example from about 5.degree. to about 25.degree. C. below the resin Tg, and where the speed at which toner size aggregates are formed can also be controlled by the temperature. Thereafter, heating from about 5.degree. to about 50.degree. C. above the resin Tg provides for particle fusion or coalescence of the polymer and pigment particles; followed by washing with an optional heating of the water up to about 60.degree. C., wherein the toner particles, especially the acid functionality, particularly acrylic acid, present on the toner surface is reacted with a base like potassium hydroxide to form the acrylic acid salt, which salt is subsequently ion exchanged, in the presence of optional metal oxide particles, such as silica, to control the toner triboelectrical charge. After drying, toner particles comprised of resin and pigment with various particle size diameters can be obtained, such as from 1 to about 20, and preferably 12 microns in average volume particle diameter, are obtained. The aforementioned toners are especially useful for the development of colored images with excellent line and solid resolution, and wherein substantially no background deposits are present. In embodiments, the toner aggregates are washed with diluted base, that is base with water added thereto, which ionizes carboxylic groups on the surface, releases residuals from the surface, and increases the solubility of the surfactants and polyacrylic acid not bounded on the surface of the toner particles, thereby more rapid and more efficient washing with less water can be accomplished; and wherein in embodiments the charge on the toner can be increased by anion exchange of the counterion.
There is illustrated in U.S. Pat. No. 4,996,127 a toner of associated particles of secondary particles comprising primary particles of a polymer having acidic or basic polar groups and a coloring agent. The polymers selected for the toners of the '127 patent can be prepared by an emulsion polymerization method, see for example columns 4 and 5 of this patent. In column 7 of this '127 patent, it is indicated that the toner can be prepared by mixing the required amount of coloring agent and optional charge additive with an emulsion of the polymer having an acidic or basic polar group obtained by emulsion polymerization. Also, see column 9, lines 50 to 55, wherein a polar monomer, such as acrylic acid, in the emulsion resin is necessary, and toner preparation is not obtained without the use, for example, of acrylic acid polar group, see Comparative Example I. In U.S. Pat. No. 4,983,488, there is disclosed a process for the preparation of toners by the polymerization of a polymerizable monomer dispersed by emulsification in the presence of a colorant and/or a magnetic powder to prepare a principal resin component and then effecting coagulation of the resulting polymerization liquid in such a manner that the particles in the liquid after coagulation have diameters suitable for a toner. It is indicated in column 9 of this patent that coagulated particles of 1 to 100, and particularly 3 to 70 are obtained. This process is thus directed to the use of coagulants, such as inorganic magnesium sulfate, which results in the formation of particles with a wide GSD. Furthermore, the '488 patent does not, it appears, disclose the process of counterionic, for example controlled aggregation is obtained by changing the counterionic strength, flocculation. Similarly, the aforementioned disadvantages, for example poor GSD are obtained hence classification is required resulting in low toner yields, are illustrated in other prior art, such as U.S. Pat. No. 4,797,339, wherein there is disclosed a process for the preparation of toners by resin emulsion polymerization, wherein similar to the '127 patent certain polar resins are selected, and wherein flocculation as in the present invention is not believed to be disclosed; and U.S. Pat. No. 4,558,108, wherein there is disclosed a process for the preparation of a copolymer of styrene and butadiene by specific suspension polymerization.
Emulsion/aggregation processes for the preparation of toners are illustrated in a number of patents, the disclosures of which are totally incorporated herein by reference, such as U.S. Pat. Nos. 5,290,654, 5,278,020, 5,308,734, 5,346,797, 5,370,963, 5,344,738, 5,403,693, 5,418,108, 5,364,729, and 5,346,797.